Dynamics Behavior Of Beach Sediment Under Wave Action

The most active regions between the sea and the land is coastal zone, and coastal erosion has become a serious enviromental geological disasters. So, there is special and important scientific significance for protecting the coaste and the beach erosion, improving the environment by studying on the sedimentary environment of the coastal zone and describing the evolution of its beach regular pattern. Coastal erosion is a process from origin to material together. This thesis studys on Qingdao Yangkou Bay which receives little damage to reveal the sediment provenance and sedimentary environment by analyzing the paramerers of grain size, heavy mineral in the hydrodynamic conditions.Based on the study of grain size, there are three types of sediment in the study area accoding to Folk and Pejrup's sediment classification methods, which are (g)S, gS, sG. Composition of sediment is the same in different season, and shows zonal distribution along the seacoast. Analyses on sediment environmental zones aside with parameters of grain size show that the distribution of sediments is chiefly controlled by environmentalhydrodynamics and the procenance of sediments.Heavy mineral analysis shows that there are 28 kinds of heavy minerals found in the study area. The mineral assemblage is lmenite-hornblende-epidote-garnet-pyroxene. Clastic sediments in heavy minerals and rock debris along the heavy mineral assemblage is consistent, also there exist metamorphic minerals as evidence of the origin. The mean is that Yangkoubay sediments is most from wave erosion or the product of cutting coastal rock. Oppositely, is less from the sea. In addition, it's certain that sediment transports from coastland to the sea in the study area according to the diversification of heavy mineral content. The shape of quartz is mostly round and sub-rounded, and it is rich in conchoidal fracture,crater and impact marks. this is the characterization of high-energy depositional environment.Based on the study of grain size and heavy mineralogy on vertical profile of the beach, there is a single type, almost gravel. this is also the characterization of high-energy depositional environment. The material mainly from the near-source. Ph and beach sediments have the same heavy mineral, this shows that there is no change in origin, which has the feature of succession. But there is different heavy mineral content in different depths. This show the chang of sedimentary environmentComprehensive analysison sediment types, mineral compositions, transportation trends, sediment provenance and sedimentary environment of the beach sediments, the result is that the sand is from coastal erosions by waves. This provides a theoretical and practical basis for us to carry out coastal protection.